Recently, there have been made great advancement in production of high performance electronic apparatuses such as mobile telephones and personal computers and variety of those apparatuses have been increased. In accordance therewith, such apparatuses having a movable housing arranged to be opened and closed with respect to a fixed housing, i.e., apparatuses of folding type, and those having a movable housing capable of swiveling around a swivel axis in addition to the above mentioned folding around a hinge axis are increasing in number. One of the examples of the apparatuses mentioned just above is disclosed in Japanese Laid-open Patent Publication No. 2002-209000.
Such apparatuses are desired to provide a good feel in folding operation and also to hold the opened and closed positions securely.
A conventional folding mechanism of the described type and an electronic apparatus using the mechanism will be described with reference to FIG. 6 to FIG. 10.
In a sectional view of the drawings, the dimension is shown elongated in the radial direction to make easy the understanding of the relationship between a fixed cam and a movable cam.
FIG. 8 and FIG. 9 is a sectional view and an exploded view in perspective of a conventional folding mechanism.
Fixed member 1 in a substantially cylindrical shape having a hollowed portion in its center is provided with a pair of fixed cams 2A and 2B in symmetrical positions 180° apart from each other on the circumference of its left-hand side face.
Further, movable member 3 in a substantially cylindrical shape is arranged for rotation in opening and closing directions with respect to fixed member 1. Movable member 3 is provided with a pair of movable cams 4A and 4B, each thereof being formed of a protruded portion and sloped portions extended therefrom toward the left and right, disposed in symmetrical positions 180° apart from each other on the circumference of its right-hand side face in confronting relation with fixed cams 2A and 2B.
Further, in a space between fixed member 1 and cover 5 which is formed in a substantially disk shape, there is mounted coil spring 6 as weakly precompressed. Urged by spring 6, tip ends of fixed cams 2A and 2B are held in resilient contact with the sloped portions of movable cams 4A and 4B, respectively. Further, there is provided movable shaft 7 in a substantially circular pillar shape having its left end portion fixedly attached to movable member 3 and having its right end portion, past through the hollowed portion in fixed member 1 and spring 6, in engagement with cover 5.
Further, mount portion 3A of movable member 3 is arranged to rotatably stick out of opening 8A at the left-hand end of fixed case 8 in a substantially cylindrical shape and protrusion 1A of fixed member 1 is inserted in groove portion 8B provided on its inner periphery. Thus, fixed member 1 is housed in fixed case 8 for movement in the axial direction. Further, while swivel axis 8C is disposed on the under side of fixed case 8, an opening at the right-hand end of fixed case 8 is covered with cover 5.
Folding mechanism 10 is thus constructed with fixed member 1, movable member 3, spring 6, and the like housed in fixed case 8.
Swivel axis 8C on the under side of fixed case 8 of folding mechanism 10 is rotatably mounted on support shaft 12C of fixed housing 12 as shown, for example, in the perspective view of a mobile telephone of FIG. 6B.
On the upper side of fixed housing 12, there are formed operating portion 12A made up of a plurality of keys and voice input portion 12B made up of such members as a microphone.
Further, mount portion 3A of movable member 3 is fixedly attached to movable housing 13 having display portion 13A formed of LCD and the like and voice output portion 13B formed of a speaker and the like disposed on the surface thereof. Thus, the electronic apparatus is constructed by having movable housing 13 hingedly supported by folding mechanism 10 for opening and closing with respect to fixed housing 12 and, further, by having movable member 13 supported by swivel axis 8C for swiveling around the same.
Operations of the folding mechanism configured as above and an electronic apparatus employing the same will be described with reference to sectional views of main portions of FIG. 10A to FIG. 10C.
In reality, a plurality of fixed cams 2A and 2B, as well as a plurality of movable cams 4A and 4B, are three-dimensionally disposed in symmetrical positions on the circumferences of the left-hand side face of fixed member 1 and the right-hand side face of movable member 3 which are both substantially cylindrical. However, the cams are shown two-dimensionally developed in FIG. 10A to FIG. 10C to make movements of these components easy to understand. In the first place, FIG. 10A shows a state in which the tip ends of fixed cam 2A and fixed cam 2B in symmetrical positions therewith at an interval of 180° are in resilient contact with sloped portions on the left-hand sides of movable cams 4A and 4B, respectively. In this state, movable member 3 is urged by spring 6 via fixed member 1 to move in the closing direction toward the right. As a result, movable housing 13 having mount portion 3A of folding mechanism 10 fixedly attached thereto is held in a closed state with respect to fixed housing 12. FIG. 6A shows the above closed state.
Then, from this closed state, movable housing 13 is opened by hand as shown by the arrow in FIG. 6B. As shown in FIG. 10B, this state corresponds to a state reached by movable member 3 turning leftward and fixed member 1 moving upward with spring 6 further compressed, thereby allowing tip ends of fixed cams 2A and 2B to go over the protrusions of movable cams 4A and 4B and come into resilient contact with the sloped portions on their right-hand side. As a result, movable member 3 is urged in the opening direction toward the left and, hence, a force in the opening direction is applied to movable housing 13.
Further, as shown in FIG. 10C, according as the tip ends of fixed cams 2A and 2B slide on the sloped portions on the right-hand side of movable cams 4A and 4B while being kept in resilient contact therewith, movable housing 13 comes to open wider. And, when fixed cam 2A comes into resilient contact with the flat portion at the end of the sloped portion, i.e.,on the left-hand side of movable cam 4B, and when fixed cam 2B comes into resilient contact with the flat portion on the left-hand side of movable cam 4A, which are symmetrically positioned 180° apart from each other, movable housing 13 comes to be held open as wide as approximately 180° from its closed position.
In other words, since fixed cams 2A and 2B and movable cams 4A and 4B are each provided in symmetrical positions 180° apart from each other on the circumferences of the side faces of fixed member 1 and movable member 3, movable housing 13 can be opened as wide as approximately 180°. However, conventional folding mechanism 10 is arranged not to open wider than that.
Further, in the state where movable housing 13 is opened approximately 180°, the tip ends of fixed cams 2A and 2B are in resilient contact with the flat portions on the left-hand side of movable cams 4A and 4B. Hence, movable member 3, i.e., movable housing 13, is in such a state that substantially no force is applied thereto in the opening direction.
Further, when movable housing 13 is swiveled as shown in the perspective view of FIG. 7A with movable housing 13, shown in FIG. 6A, kept closed, movable housing 13 is pivoted on supporting shaft 12C of fixed housing 12. Then, while operating portion 12A faces the operator, display portion 13A has its back toward the operator.
Further, in this state, folding mechanism 10 is in its closed state, i.e., in the state as shown in FIG. 10A, where the tip ends of fixed cams 2A and 2B are in resilient contact with the sloped portions on the left-hand side of movable cams 4A and 4B, respectively.
If movable housing 13 in such a state is folded down to be closed, with display portion 13A kept face up as shown in FIG. 7B, folding mechanism 10 itself is then comes into the same state as is brought about when movable housing 13 is opened to around 180° from its closed state as described above. Thus, as shown in FIG. 10C, the state in which the tip ends of fixed cams 2A and 2B are in resilient contact with the flat portions on the left-hand side of movable cams 4A and 4B and movable housing 13 is folded down is brought about.
However, in the described state, substantially no force in the opening direction is applied to movable member 3 as described above, and hence, substantially no force in the closing direction is applied to movable housing 13.
Thus, angle of opening over 180° cannot be attained by the above described conventional folding mechanism. Further, substantially no force in the closing direction is applied to movable housing 13 in the state of movable housing 13 folded down with display portion 13A face up, i.e., in the state of folding mechanism 10 opened approximately 180° from its closed position.
As a result, there arises a problem in an electronic apparatus employing such conventional folding mechanism 10 that a gap or play tends to be produced between movable housing 13 and fixed housing 12 and it becomes difficult to hold the opened and closed positions securely.
On the other hand, if such a configuration is made that has a single fixed cam and a single movable cam to come into resilient contact with each other, instead of such that has a plurality of fixed cams and movable cams in symmetrical positions 180° apart from each other to come into resilient contact as described above, a folding mechanism capable of attaining an angle of opening wider than 180° can be realized.
In such case, however, since resilient contact between cams is made only in one position, each cam tends to incline from its right position and the inclined cam tends to come into abutment with the movable shaft. As a result, wear and tear are liable to be produced. Further, a problem arises that it becomes difficult to obtain opening and closing operations felt good and kept stabilized.
The present invention was made to overcome such problems of the prior art. Accordingly, the invention is directed to provision of a folding mechanism in which opening and closing operations are made with a good feel and opened and closed positions are securely held, as well as to provision of an electronic apparatus employing the same.